U.S. patent application number 16/835369 was filed with the patent office on 2020-10-29 for multi charged particle beam writing apparatus.
This patent application is currently assigned to NuFlare Technology, Inc.. The applicant listed for this patent is NuFlare Technology, Inc.. Invention is credited to Hirofumi MORITA, Mitsuhiro OKAZAWA.
Application Number | 20200343073 16/835369 |
Document ID | / |
Family ID | 1000004765139 |
Filed Date | 2020-10-29 |
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United States Patent
Application |
20200343073 |
Kind Code |
A1 |
OKAZAWA; Mitsuhiro ; et
al. |
October 29, 2020 |
MULTI CHARGED PARTICLE BEAM WRITING APPARATUS
Abstract
Provided is a multi charged particle beam writing apparatus
including: an emission unit emitting a charged particle beam; a
restriction aperture unit having a first opening having a variable
opening area, the restriction aperture unit shielding a portion of
the charged particle beam; a shaping aperture array substrate
having a plurality of second openings, the shaping aperture array
substrate forming multiple beams by allowing the shaping aperture
array substrate to be irradiated with the charged particle beam
passing through the first opening and allowing a portion of the
charged particle beam to pass through the plurality of second
openings; and a blanking aperture array substrate having a
plurality of third openings, each beam of the multiple beams
passing through the plurality of third openings, the blanking
aperture array substrate being capable of independently deflecting
each beam of the multiple beams.
Inventors: |
OKAZAWA; Mitsuhiro;
(Yokohama-shi, JP) ; MORITA; Hirofumi;
(Setagaya-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuFlare Technology, Inc. |
Yokohama-shi |
|
JP |
|
|
Assignee: |
NuFlare Technology, Inc.
Yokohama-shi
JP
|
Family ID: |
1000004765139 |
Appl. No.: |
16/835369 |
Filed: |
March 31, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 37/045 20130101;
H01J 2237/0435 20130101; H01J 37/09 20130101; H01J 37/3177
20130101; H01J 2237/0453 20130101; H01J 37/12 20130101 |
International
Class: |
H01J 37/317 20060101
H01J037/317; H01J 37/09 20060101 H01J037/09; H01J 37/04 20060101
H01J037/04; H01J 37/12 20060101 H01J037/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2019 |
JP |
2019-084353 |
Claims
1. A multi charged particle beam writing apparatus comprising: an
emission unit emitting a charged particle beam; a restriction
aperture unit having a first opening having a variable opening
area, the restriction aperture unit shielding a portion of the
charged particle beam; a shaping aperture array substrate having a
plurality of second openings, the shaping aperture array substrate
forming multiple beams by allowing the shaping aperture array
substrate to be irradiated with the charged particle beam passing
through the first opening and the shaping aperture array substrate
allowing a portion of the charged particle beam to pass through the
plurality of second openings; and a blanking aperture array
substrate having a plurality of third openings, each beam of the
multiple beams passing through the plurality of third openings, the
blanking aperture array substrate being capable of independently
deflecting each beam of the multiple beams.
2. The multi charged particle beam writing apparatus according to
claim 1, wherein the first opening of the restriction aperture unit
is formed by combining a first portion and a second portion that
are relatively movable.
3. The multi charged particle beam writing apparatus according to
claim 2, wherein the first portion and the second portion are
separated from each other.
4. The multi charged particle beam writing apparatus according to
claim 2, wherein the first portion and the second portion have an
L-shaped plate shape.
5. The multi charged particle beam writing apparatus according to
claim 2, wherein each of the first portion and the second portion
have a frame shape and a plate shape.
6. The multi charged particle beam writing apparatus according to
claim 2, wherein the thickness of the first portion and the
thickness of the second portion are 0.3 mm or more and 3 mm or
less.
7. The multi charged particle beam writing apparatus according to
claim 2, further comprising a driving motor relatively moving the
first portion and the second portion.
8. The multi charged particle beam writing apparatus according to
claim 1, wherein the first opening has a rectangular shape.
9. The multi charged particle beam writing apparatus according to
claim 1, wherein a maximum opening area of the first opening is 1.2
times or more and 3 times or less of a minimum opening area of the
first opening.
10. The multi charged particle beam writing apparatus according to
claim 1, wherein the restriction aperture unit contains a heavy
metal.
11. The multi charged particle beam writing apparatus according to
claim 1, further comprising: an illumination lens provided between
the emission unit and the restriction aperture unit; and a
projection lens, the blanking aperture array substrate being
located between the projection lens and the illumination lens.
12. The multi charged particle beam writing apparatus according to
claim 11, further comprising an electrostatic lens provided between
the illumination lens and the shaping aperture array substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Applications No. 2019-084353, filed
on Apr. 25, 2019, the entire contents of which are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] Embodiments relate to a multi charged particle beam writing
apparatus.
BACKGROUND OF THE INVENTION
[0003] With high integration of semiconductor devices, circuit
patterns of semiconductor devices have become fine. In realizing a
fine circuit pattern, a lithography technique for forming a circuit
pattern on a semiconductor substrate becomes important. In order to
form a fine circuit pattern by using a lithography technique, an
original image pattern (also referred to as a reticle or a mask)
with high accuracy is required. Electron beam writing inherently
has excellent resolution, and thus, is used for manufacturing an
original image pattern with high accuracy.
[0004] For example, there is a writing apparatus using multiple
beams. Compared to pattern drawing with one electron beam, a target
object can be irradiated with many electron beams at once by using
the multiple beams. Therefore, it is possible to greatly improve
the throughput of the pattern drawing.
[0005] In a writing apparatus using multiple beams, the multiple
beams are formed by allowing an electron beam emitted from an
electron gun assembly to pass through a shaping aperture array
having a plurality of openings. Each beam of the multiple beams is
independently deflected by a blanking aperture array substrate.
[0006] The blanking aperture array substrate has a plurality of
openings through which each beam of the multiple beams passes and
an electrode pair provided in each of the openings. By controlling
the voltage applied to the electrode pair, each beam of the
multiple beams is deflected. The beam deflected by the electrode
pair is shielded, and the target object is irradiated with the beam
that is not deflected, so that the pattern drawing is
performed.
[0007] The temperature of the shaping aperture array substrate
rises due to the irradiation with the electron beam. If the
temperature of the shaping aperture array substrate rises, the
pitch of the openings changes due to thermal expansion. If the
pitch of the openings deviates from a predetermined range, for
example, each beam of the multiple beams cannot pass through the
desired openings of the blanking aperture array, and thus, there is
a problem that the electron beam with which the target object is
irradiated is lost.
[0008] For this reason, for example, the pitch of the openings of
the shaping aperture array is designed in consideration of a change
due to a rise in temperature of the shaping aperture array
substrate in advance. During the time of pattern drawing, the
temperature of the shaping aperture array substrate is maintained
in a predetermined range, so that the pitch of the openings falls
within a predetermined range.
[0009] In order to prevent the temperature of the shaping aperture
array substrate from rising, for example, it is considered that a
restriction aperture that restricts the amount of the electron beam
with which the shaping aperture array substrate is irradiated is
provided. The restriction aperture is provided between the electron
gun assembly and the shaping aperture array substrate and shields a
portion of the electron beam to restrict the amount of the electron
beam with which the shaping aperture array substrate is
irradiated.
[0010] On the other hand, if the shaping aperture temperature is
suppressed to be too low, there is a problem in that the growth of
dirt (mainly hydrocarbon) in the holes of the shaping aperture is
facilitated. If dirt grows in the holes of the shaping aperture,
there occur problems in pattern drawing accuracy such as a
deterioration in beam shape accuracy and a deterioration in beam
position accuracy. For this reason, it is necessary to replace the
shaping aperture, but since it is necessary to stop the apparatus
and perform the replacement operation, there is a problem in that
the operating rate of the apparatus significantly decreases. Thus,
in order to suppress a change in pitch of the shaping aperture
openings due to a temperature rise, it is better to lower the
temperature, but if the temperature is too low, there occur
problems such as a deterioration in accuracy due to the growth of
dirt on the shaping aperture and a decrease in operating rate.
SUMMARY OF THE INVENTION
[0011] A multi charged particle beam writing apparatus according to
one embodiment includes: an emission unit emitting a charged
particle beam; a restriction aperture unit having a first opening
having a variable opening area, the restriction aperture unit
shielding a portion of the charged particle beam; a shaping
aperture array substrate having a plurality of second openings, the
shaping aperture array substrate forming multiple beams by allowing
the shaping aperture array substrate to be irradiated with the
charged particle beam passing through the first opening and
allowing a portion of the charged particle beam to pass through the
plurality of second openings; and a blanking aperture array
substrate having a plurality of third openings, each beam of the
multiple beams passing through the plurality of third openings, the
blanking aperture array substrate being capable of independently
deflecting each beam of the multiple beams.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a conceptual view illustrating a configuration of
a multi charged particle beam writing apparatus according to a
first embodiment;
[0013] FIGS. 2A, 2B, 2C, and 2D are schematic views of a
restriction aperture unit according to the first embodiment;
[0014] FIGS. 3A and 3B are explanatory views of the restriction
aperture unit according to the first embodiment;
[0015] FIG. 4 is a schematic view of a shaping aperture array
substrate according to the first embodiment;
[0016] FIGS. 5A and 5B are explanatory views of an illumination
region of the shaping aperture array substrate according to the
first embodiment;
[0017] FIGS. 6A, 6B, 6C, and 6D are schematic views of a
restriction aperture unit according to a second embodiment;
[0018] FIGS. 7A and 7B are explanatory views of the restriction
aperture unit according to the second embodiment;
[0019] FIGS. 8A, 8B, 8C, and 8D are schematic views of a
restriction aperture unit according to a third embodiment;
[0020] FIGS. 9A and 9B are explanatory views of the restriction
aperture unit according to the third embodiment;
[0021] FIG. 10 is a conceptual view illustrating a configuration of
a multi charged particle beam writing apparatus according to a
fourth embodiment; and
[0022] FIG. 11 is a conceptual view illustrating a configuration of
a multi charged particle beam writing apparatus according to a
fifth embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] Hereinafter, embodiments will be described with reference to
the drawings. Hereinafter, in the embodiments, a configuration
using an electron beam will be described as an example of a charged
particle beam. However, the charged particle beam is not limited to
an electron beam, but a beam using charged particles such as an ion
beam may be used.
[0024] In this specification, the pattern drawing data is basic
data of the pattern to be drawn on the target object. The pattern
drawing data is data obtained by converting a format of design data
generated by a designer by CAD or the like so that arithmetic
processing can be performed in the writing apparatus. A drawing
pattern of a figure or the like is defined by, for example,
coordinates such as vertices of the figure.
First Embodiment
[0025] A multi charged particle beam writing apparatus according to
a first embodiment includes: an emission unit emitting a charged
particle beam; a restriction aperture unit having a first opening
having a variable opening area, the restriction aperture unit
shielding a portion of the charged particle beam; a shaping
aperture array substrate having a plurality of second openings, the
shaping aperture array substrate forming multiple beams by allowing
the shaping aperture array substrate to be irradiated with the
charged particle beam passing through the first opening and
allowing a portion of the charged particle beam to pass through the
plurality of second openings; and a blanking aperture array
substrate having a plurality of third openings, each beam of the
multiple beams passing through the plurality of third openings, the
blanking aperture array substrate being capable of independently
deflecting each beam of the multiple beams.
[0026] Hereinafter, a case where the multi charged particle beam
writing apparatus is a mask writing apparatus will be described as
an example.
[0027] FIG. 1 is a conceptual view illustrating a configuration of
the multi charged particle beam writing apparatus according to the
first embodiment.
[0028] As illustrated in FIG. 1, a mask writing apparatus (charged
particle beam writing apparatus) includes a pattern drawing unit
100 and a control unit 200. The mask writing apparatus draws a
desired pattern on a target object 42.
[0029] The pattern drawing unit 100 has an electron lens barrel 12
and a pattern drawing chamber 14. An electron gun assembly 16
(emission unit), an illumination lens 18, a restriction aperture
unit 22, a shaping aperture array substrate 28, a blanking aperture
array substrate 30, a projection lens 32, a deflector 34, a
stopping aperture substrate 36 and an objective lens 38 are
arranged in the electron lens barrel 12. The pattern drawing unit
100 performs pattern drawing on the target object 42.
[0030] An XY stage 40 movably arranged is arranged in the pattern
drawing chamber 14. The target object 42 can be mounted on the XY
stage 40. The target object 42 is a mask substrate for exposure for
transferring a pattern to a wafer. The mask substrate is, for
example, a mask blank on which nothing is drawn yet.
[0031] The inside of the electron lens barrel 12 and the inside of
the pattern drawing chamber 14 are evacuated by a vacuum pump (not
illustrated) to be substantially vacuum.
[0032] The control unit 200 includes a stage driving circuit 44, a
deflection control circuit 46, a restriction aperture driving
circuit 48, a control calculator 50, a memory 52, and a magnetic
disk drive 54. The control unit 200 controls the pattern drawing
unit 100 that performs pattern drawing on the target object 42.
[0033] The electron gun assembly 16 emits an electron beam B. The
electron gun assembly 16 is an example of an emission unit.
[0034] The illumination lens 18 is provided on the XY stage 40 side
(hereinafter, referred to as a downstream side) of the electron gun
assembly 16. The illumination lens 18 refracts the electron beam B
emitted from the electron gun assembly 16 and irradiates the
restriction aperture unit 22 with the electron beam B. At this
time, the illumination angle can be set to a predetermined angle by
the illumination lens 18. In the present embodiment, the light is
emitted vertically, but a reduction optical system described later
may be used. Herein, the illumination lens 18 is an electron
lens.
[0035] The restriction aperture unit 22 is provided on the
downstream side of the illumination lens 18. The restriction
aperture unit 22 is provided between the illumination lens 18 and
the shaping aperture array substrate 28. The restriction aperture
unit 22 shields a portion of the electron beam B with which the
restriction aperture unit 22 is irradiated through the illumination
lens 18.
[0036] FIGS. 2A, 2B, 2C, and 2D are schematic views of the
restriction aperture unit according to the first embodiment. FIG.
2A is a top view of the restriction aperture unit, FIG. 2B is a top
view of a portion (first portion) of the restriction aperture unit,
FIG. 2C is a top view of another portion (second portion) of the
restriction aperture unit, and FIG. 2D is a cross-sectional view of
the restriction aperture unit. FIG. 2D illustrates an AA'
cross-section of FIG. 2A.
[0037] As illustrated in FIG. 2A, the restriction aperture unit 22
has a first opening 22x. The first opening 22x has, for example, a
rectangular shape. The first opening 22x has, for example, a square
shape. A portion of the electron beam B with which the restriction
aperture unit 22 is irradiated passes through the first opening
22x.
[0038] The restriction aperture unit 22 is configured by combining
two L-shaped components (a first portion 22a and a second portion
22b). Each of the first portion 22a and the second portion 22b has
a plate shape.
[0039] As illustrated in FIGS. 2A and 2D, at least a portion of the
second portion 22b faces the first portion 22a. At least a portion
of the second portion 22b overlaps the first portion 22a in the
up-down direction. The first opening 22x is formed by the second
portion 22b overlapping the first portion 22a.
[0040] The first portion 22a is separated from the second portion
22b, for example, with a predetermined gap in the up-down direction
(vertical direction) without contact.
[0041] The restriction aperture unit 22 contains, for example,
heavy metal. The first portion 22a and the second portion 22b
constituting the restriction aperture unit 22 are configured with,
for example, a material containing a heavy metal that is
non-magnetic and does not generate X-rays. The heavy metal is, for
example, tantalum (Ta), tungsten (W), or gold (Au). In addition,
the heavy metal denotes a metal having a specific gravity equal to
or higher than that of iron (Fe).
[0042] In addition, as a material of the restriction aperture unit
22, for example, carbon (C) or silicon (Si) can be used. In
addition, a light metal such as aluminum (l) or titanium (Ti),
which has a low reflectance (back scattering coefficient) add is
easy to process can also be used.
[0043] The thickness of the first portion 22a and the second
portion 22b is, for example, 0.3 mm or more and 3 mm or less.
[0044] The support portion 26 supports the restriction aperture
unit 22. The support portion 26 has a first support bar 26a and a
second support bar 26b. In the support portion 26, for example, the
first portion 22a is supported by the first support bar 26a. For
example, the second portion 22b is supported by the second support
bar 26b.
[0045] The first portion 22a and the second portion 22b are
supported by the first support bar 26a and the second support bar
26b at least one location. The first portion 22a and the second
portion 22b may be supported by the support portion 26 at a
plurality of locations.
[0046] The driving motor 24 is connected to the support portion 26.
The driving motor 24 relatively moves the first portion 22a and the
second portion 22b by, for example, moving the support portion 26
in the horizontal direction.
[0047] The driving motor 24 is, for example, a non-magnetic motor.
The driving motor 24 is, for example, a piezo motor. By using a
non-magnetic motor as the driving motor 24, the influence of the
operation of the driving motor 24 on the trajectory of the electron
beam B is reduced.
[0048] FIGS. 3A and 3B are explanatory views of the restriction
aperture unit according to the first embodiment. FIG. 3A
illustrates a state where the opening area of the first opening 22x
is small, and FIG. 3B illustrates a state where the opening area of
the first opening 22x is large.
[0049] The opening area of the first opening 22x of the restriction
aperture unit 22 is variable. For example, by horizontally move the
support portion 26 in the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 3A is small to the state
where the opening area illustrated in FIG. 3B is large. In
addition, by horizontally moving the support portion 26 in the
direction opposite to the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 3B is large to the state
where the opening area illustrated in FIG. 3A is small.
[0050] The maximum opening area of the first opening 22x is, for
example, 1.2 times or more and 3 times or less of the minimum
opening area.
[0051] The shaping aperture array substrate 28 is provided on the
downstream side of the restriction aperture unit 22. The shaping
aperture array substrate 28 is provided between the restriction
aperture unit 22 and the blanking aperture array substrate 30. The
shaping aperture array substrate 28 is irradiated with the electron
beam B that has passed through the restriction aperture unit 22.
The shaping aperture array substrate 28 forms the multiple beams
MB.
[0052] FIG. 4 is a schematic view of the shaping aperture array
substrate according to the first embodiment. FIG. 4 is a top view
of the shaping aperture array substrate.
[0053] The shaping aperture array substrate 28 has a plate shape.
The shaping aperture array substrate 28 has a plurality of second
openings 28x. In the shaping aperture array substrate 28, for
example, m rows.times.n rows (m, n.gtoreq.2) of second openings 28x
are arranged at a predetermined pitch.
[0054] The second opening 28x has, for example, a rectangular
shape. The second opening 28x has, for example, a square shape. The
second opening 28x may have, for example, a circular shape.
[0055] A portion of the electron beam B that has passed through the
restriction aperture unit 22 passes through the plurality of second
openings 28x of the shaping aperture array substrate 28 to be
divided, so that multiple beams MB is formed.
[0056] The material of the shaping aperture array substrate 28 is,
for example, silicon (Si).
[0057] The blanking aperture array substrate 30 is provided on the
downstream side of the shaping aperture array substrate 28. Each
beam of the multiple beams MB can be independently deflected by the
blanking aperture array substrate 30.
[0058] The blanking aperture array substrate 30 has a plate shape.
The blanking aperture array substrate 30 has a plurality of third
openings 30x through which each of the multiple beams MB formed by
the shaping aperture array substrate 28 passes. In the blanking
aperture array substrate 30, for example, m rows.times.n rows (m,
n.gtoreq.2) of third openings 30x are arranged at a predetermined
pitch.
[0059] The number of the second openings 28x of the shaping
aperture array substrate 28 and the number of the third openings
30x of the blanking aperture array substrate 30 are equal to each
other.
[0060] A blanker is provided in each of the third openings 30x. The
blanker is formed by a pair of electrodes. For example, one
electrode of the blanker is fixed at the ground potential, and a
potential different from the ground potential is applied to the
other electrode. Each beam of the multiple beams MB passing through
the third opening 30x is independently deflected by a voltage
applied to the blanker.
[0061] The projection lens 32 is provided on the downstream side of
the blanking aperture array substrate 30. The projection lens 32
allows the multiple beams MB that has passed through the blanking
aperture array substrate 30 to converge. The projection lens 32 is
an electron lens.
[0062] The deflector 34 is provided on the downstream side of the
projection lens 32. The deflector 34 deflects the multiple beams MB
converged by the projection lens 32 collectively in the same
direction.
[0063] The stopping aperture substrate 36 is provided on the
downstream side of the deflector 34. The stopping aperture
substrate 36 shields the electron beam deflected by the blanker of
the blanking aperture array substrate 30 among the multiple beams
MB.
[0064] The stopping aperture substrate 36 has a plate shape. The
stopping aperture substrate 36 has a fourth opening 36x. Among the
multiple beams MB, the electron beam not deflected by the blanker
of the blanking aperture array substrate 30 passes through the
fourth opening 36x.
[0065] In addition, the deflector 34 can be provided on the
downstream side of the stopping aperture substrate 36.
[0066] The objective lens 38 is provided on the downstream side of
the stopping aperture substrate 36. The objective lens 38 focuses
each beam that has passed through the stopping aperture substrate
36 on the target object 42.
[0067] The stage driving circuit 44 controls the movement of the XY
stage 40 in the pattern drawing chamber 14. The deflection control
circuit 46 controls the deflection of the multiple beams MB by the
blanking aperture array substrate 30 and the deflector 34.
[0068] The restriction aperture driving circuit 48 controls the
relative movement between the first portion 22a and the second
portion 22b of the restriction aperture unit 22 by the driving
motor 24. The restriction aperture driving circuit 48 controls the
relative movement between the first portion 22a and the second
portion 22b of the restriction aperture unit 22. In other words,
the restriction aperture driving circuit 48 controls the opening
area of the restriction aperture unit 22.
[0069] The magnetic disk drive 54 stores, for example, pattern
drawing data. The pattern drawing data is input from the magnetic
disk drive 54 to the control calculator 50.
[0070] The memory 52 stores, for example, information input to the
control calculator 50, information during arithmetic processing,
and information after arithmetic processing.
[0071] The control calculator 50 is connected to the stage driving
circuit 44, the deflection control circuit 46, and the restriction
aperture driving circuit 48. A command signal is transmitted from
the control calculator 50 to the stage driving circuit 44, the
deflection control circuit 46, and the restriction aperture driving
circuit 48, and pattern drawing is performed.
[0072] FIG. 1 illustrates components necessary for describing the
first embodiment. It goes without saying that the mask writing
apparatus according to the first embodiment usually includes other
components necessary for the mask writing apparatus.
[0073] Next, the operations of the multi charged particle beam
writing apparatus according to the first embodiment will be
described.
[0074] The restriction aperture unit 22 is irradiated with the
electron beam B emitted from the electron gun assembly 16 by the
illumination lens 18. At this time, the illumination angle can be
set to a predetermined angle by the illumination lens 18. In the
present embodiment, the light is emitted vertically, but a
reduction optical system described later may be used. The shaping
aperture array substrate 28 is irradiated with the electron beam B
that has passed through the first opening 22x of the restriction
aperture unit 22.
[0075] The opening area of the first opening 22x of the restriction
aperture unit 22 is variable. The driving motor 24 operates in
response to a command signal from the restriction aperture driving
circuit 48 to relatively move the first portion 22a and the second
portion 22b, so that the opening area of the first opening 22x
changes.
[0076] FIGS. 5A and 5B are explanatory views of an illumination
region of the shaping aperture array substrate according to the
first embodiment. FIG. 5A illustrates a case where the illumination
region is narrow, and FIG. 5B illustrates a case where the
illumination region is wide. The illumination region is a region
irradiated with the electron beam B.
[0077] When the opening area of the first opening 22x of the
restriction aperture unit 22 is small, as illustrated by hatching
in FIG. 5A, an illumination region 28a of the shaping aperture
array substrate 28 becomes narrow. On the other hand, when the
opening area of the first opening 22x of the restriction aperture
unit 22 is large, as illustrated by hatching in FIG. 5B, the
illumination region 28a of the shaping aperture array substrate 28
becomes wide.
[0078] The electron beam B with which the shaping aperture array
substrate 28 is irradiated passes through the plurality of second
openings 28x of the shaping aperture array substrate 28 to be
divided, so that a plurality of electron beams (multiple beams MB)
are formed.
[0079] Each beam of the multiple beams MB passes through a
respective opening of a plurality of third openings 30x of the
blanking aperture array substrate 30. For example, a portion of
each beam of the multiple beams MB is deflected by a voltage
applied to the blanker.
[0080] Each beam of the multiple beams MB that has passed through
the plurality of second openings 28x of the blanking aperture array
substrate 30 is converged by the projection lens 32 and directed to
the fourth opening 36x of the stopping aperture substrate 36. Among
the beams of the multiple beams MB, the electron beam deflected by
the blanking aperture array substrate 30 deviates from the fourth
opening 36x of the stopping aperture substrate 36 and is
shielded.
[0081] On the other hand, the electron beam not deflected by the
blanking aperture array substrate 30 passes through the fourth
opening 36x of the stopping aperture substrate 36. Irradiation and
non-irradiation of each beam to the target object 42 are
independently control led by the blanking aperture array substrate
30 and the stopping aperture substrate 36.
[0082] A command signal based on the pattern drawing data is
transmitted from the control calculator 50 to the deflection
control circuit 46. By the command signal from the deflection
control circuit 46, the voltage applied to each blanker of the
blanking aperture array substrate 30 is controlled, and whether or
not each beam is deflected is controlled.
[0083] Each beam that has passed through the stopping aperture
substrate 36 is focused by the objective lens 38, and the target
object 42 is irradiated with each beam, so that the pattern drawing
of the target object 42 is performed.
[0084] The beams are deflected collectively by the deflector 34, so
that a predetermined position of the target object 42 is irradiated
with the beams. A command signal based on the pattern drawing data
is transmitted from the control calculator 50 to the deflection
control circuit 46. The electron beam is deflected by the deflector
34 on the basis of the command signal from the deflection control
circuit 46, and a predetermined position on the target object 42
determined by the pattern drawing data is irradiated with the
electron beam.
[0085] For example, a predetermined position on the target object
42 on the XY stage 40 that continuously moves is irradiated with
the electron beam. The XY stage 40 moves on the basis of the
command signal from the stage driving circuit 44. The electron beam
follows the movement of the XY stage 40 by being deflected by the
deflector 34.
[0086] Next, the functions and effects of the charged particle beam
writing apparatus according to the first embodiment will be
described.
[0087] The temperature of the shaping aperture array substrate 28
rises by the irradiation with the electron beam B. If the
temperature of the shaping aperture array substrate 28 rises, the
pitch of the second openings 28x changes due to thermal expansion.
If the pitch of the second openings 28x deviates from a
predetermined range, for example, each beam of the multiple beams
MB cannot pass through the corresponding third opening 30x of the
blanking aperture array substrate 30, and thus, there is a problem
in that the electron beam with which the target object 42 is to be
irradiated is lost.
[0088] For this reason, for example, the pitch of the second
openings 28x of the shaping aperture array substrate 28 is designed
in consideration of a change due to a temperature rise in advance.
During the time of pattern drawing, by maintaining the temperature
of the shaping aperture array substrate 28 in a predetermined
range, the pitch of the second openings 28x is allowed to fall
within the predetermined range. Therefore, if the temperature of
the shaping aperture array substrate 28 is too high or too low, the
pitch of the second openings 28x deviates from a predetermined
range, and thus, there is a problem in that the electron beam with
which the target object 42 is to be irradiated is lost.
[0089] Furthermore, in a case where the temperature of the shaping
aperture array substrate 28 is too low, the solidified adhesive
substance from the atmosphere adheres to the second opening 28x. If
an adhesive substance adheres to the second opening 28x, the
electron beam is unintentionally deflected due to charge-up, and
thus, there is a problem in that the pattern drawing accuracy
decreases. In addition, if the amount of the adhesive substance is
large, the second opening 28x is closed, and thus, there is a
problem in that the beam with which the target object 42 is
irradiated is lost.
[0090] For example, there is a method of controlling the
temperature of the shaping aperture array substrate 28 with cooling
water. The temperature of the shaping aperture array substrate 28
is controlled by circulating cooling water for cooling the shaping
aperture array substrate 28 and controlling the temperature and the
flow rate of the cooling water.
[0091] However, in the temperature control based on the temperature
and the flow rate of the cooling water, it takes time to change the
temperature of the shaping aperture array substrate 28. For this
reason, there is a problem in that the throughput of the mask
writing apparatus decreases.
[0092] In the mask writing apparatus according to the first
embodiment, the opening area of the first opening 22x of the
restriction aperture unit 22 is variable. For this reason, the area
of the illumination region 28a of the electron beam B with which
the shaping aperture array substrate 28 is irradiated also becomes
variable.
[0093] By changing the area of the illumination region 28a, the
temperature of the shaping aperture array substrate 28 can be
changed. For example, in a case where it is desired to lower the
temperature of the shaping aperture array substrate 28, the
illumination region 28a is allowed to be narrow as illustrated in
FIG. 5A. On the other hand, for example, in a case where the
temperature of the shaping aperture array substrate 28 is
increased, as illustrated in FIG. 5B, the illumination region 28a
is allowed to be wide.
[0094] The mask writing apparatus according to the first embodiment
can appropriately control the temperature of the shaping aperture
array substrate 28 by changing the opening area of the first
opening 22x of the restriction aperture unit 22.
[0095] By changing the opening area of the first opening 22x of the
restriction aperture unit 22, the dose of the electron beam B to
the shaping aperture array substrate 28 can be directly changed.
For this reason, the time required for changing the temperature of
the shaping aperture array substrate 28 is shortened. Therefore,
the throughput of the mask writing apparatus is improved.
[0096] It is preferable that the first portion 22a and the second
portion 22b of the restriction aperture unit 22 are separated from
each other. The first portion 22a and the second portion 22b do not
come into contact with each other during the time of relatively
moving, and thus, dust emission is suppressed.
[0097] It is preferable that the first portion 22a and the second
portion 22b of the restriction aperture unit 22 contain a heavy
metal. For example, since the first portion 22a and the second
portion 22b contain a heavy metal having a higher specific gravity
than silicon (Si), generation of X-rays is suppressed. In addition,
a desired ability of shielding the electron beam can be obtained.
In addition, since the first portion 22a and the second portion 22b
contain a heavy metal, heat resistance is improved.
[0098] The thickness of the first portion 22a and the second
portion 22b of the restriction aperture unit 22 is preferably 0.3
mm or more and 3 mm or less, more preferably 0.5 mm or more and 2
mm or less. In a case where the thickness is larger than the
above-mentioned lower limit, a sufficient ability of shielding the
electron beam can be obtained. In addition, in a case where the
thickness is smaller than the above-mentioned upper limit, the
weight is reduced, and the support by the support portion 26 is
facilitated.
[0099] The maximum opening area of the first opening 22x of the
restriction aperture unit 22 is, for example, preferably 1.2 times
or more and 3 times or less, more preferably 1.5 times or more and
2.5 times or less of the minimum opening area. In a case where
maximum opening area is larger than the above-mentioned lower
limit, the temperature of the shaping aperture array substrate 28
can be controlled in a wide temperature range. In addition, in a
case where maximum opening area is smaller than the above-mentioned
lower limit, the size of the restriction aperture unit 22 can be
reduced, and the processing is facilitated.
[0100] As described above, the multi charged particle beam writing
apparatus according to the first embodiment can quickly and
appropriately control the temperature of the shaping aperture array
substrate 28 by allowing the opening area of the first opening 22x
of the restriction aperture unit 22 to be variable.
Second Embodiment
[0101] A multi charged particle beam writing apparatus according to
a second embodiment is the same as the multi charged particle beam
writing apparatus according to the first embodiment except that the
structure of the restriction aperture unit is different from that
of the first embodiment. Hereinafter, a portion of contents
overlapping with the first embodiment will be omitted in
description.
[0102] FIGS. 6A, 6B, and 6C are schematic views of the restriction
aperture unit according to the second embodiment. FIG. 6A is a top
view of a restriction aperture unit, FIG. 6B is a top view of a
portion (first portion) of the restriction aperture unit, FIG. 6C
is a top view of another portion (second portion) of the
restriction aperture unit, and FIG. 6D is a cross-sectional view of
the restriction aperture unit. FIG. 6D illustrates a BB'
cross-section of FIG. 6A.
[0103] As illustrated in FIG. 6A, the restriction aperture unit 22
has a first opening 22x. The first opening 22x has, for example, a
rectangular shape. The first opening 22x has, for example, a square
shape. A portion of the electron beam B with which the restriction
aperture unit 22 is irradiated passes through the first opening
22x.
[0104] The restriction aperture unit 22 has a first portion 22a and
a second portion 22b. As illustrated in FIG. 6B, the first portion
22a has a frame shape. In addition, the first portion 22a has a
plate shape.
[0105] Similarly, as illustrated in FIG. 6C, the second portion 22b
has a frame shape. In addition, the second portion 22b has a plate
shape.
[0106] As illustrated in FIGS. 6A and 6D, at least a portion of the
second portion 22b faces the first portion 22a. In other words, at
least a portion of the second portion 22b overlaps the first
portion 22a in the up-down direction. The first opening 22x is
formed by the second portion 22b overlapping the first portion
22a.
[0107] The first portion 22a and the second portion 22b are
separated from each other, for example, in the up-down direction.
For example, the first portion 22a and the second portion 22b are
not in contact with each other.
[0108] For the first portion 22a and the second portion 22b
constituting the restriction aperture unit 22, for example, those
having the same material and thickness as those in the first
embodiment can be used.
[0109] FIGS. 7A and 7B are explanatory views of the restriction
aperture unit according to the second embodiment. FIG. 7A
illustrates a state where the opening area of the first opening 22x
is small, and FIG. 7B illustrates a state where the opening area of
the first opening 22x is large.
[0110] The opening area of the first opening 22x of the restriction
aperture unit 22 is variable. For example, by horizontally moving
the support portion 26 in the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 7A is small to the state
where the opening area illustrated in FIG. 7B is large. In
addition, by horizontally moving the support portion 26 in the
direction opposite to the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 7B is large to the state
where the opening area illustrated in FIG. 7A is small.
[0111] As described above, similarly to the first embodiment, the
multi charged particle beam writing apparatus according to the
second embodiment can quickly and appropriately control the
temperature of the shaping aperture array substrate 28 by allowing
the opening area of the first opening 22x of the restriction
aperture unit 22 to be variable.
Third Embodiment
[0112] A multi charged particle beam writing apparatus according to
a third embodiment is the same as the multi charged particle beam
writing apparatus according to the first embodiment except that the
structure of the restriction aperture unit is different from that
of the first embodiment. Hereinafter, a portion of contents
overlapping with the first embodiment will be omitted in
description.
[0113] FIGS. 8A, 8B, 8C, and 8D are schematic views of the
restriction aperture unit according to the third embodiment. FIG.
8A is a top view of the restriction aperture unit, FIG. 8B is a top
view of a portion (first portion and third portion) of the
restriction aperture unit, FIG. 8C is a top view of another portion
(second portion and fourth portion) of the restriction aperture
unit, and FIG. 8D is a cross-sectional view of the restriction
aperture unit. FIG. 8D illustrates CC' cross-section of FIG.
8A.
[0114] As illustrated in FIG. 8A, the restriction aperture unit 22
has a first opening 22x. The first opening 22x has, for example, a
rectangular shape. The first opening 22x has, for example, a square
shape. A portion of the electron beam B with which the restriction
aperture unit 22 is irradiated passes through the first opening
22x.
[0115] The restriction aperture unit 22 has a first portion 22a, a
second portion 22b, a third portion 22c, and a fourth portion 22d.
As illustrated in FIG. 8B, the first portion 22a and the third
portion 22c have a rectangular shape. In addition, the first
portion 22a and the third portion 22c have a plate shape.
[0116] Similarly, as illustrated in FIG. 8C, the second portion 22b
and the fourth portion 22d have a rectangular shape. In addition,
the second portion 22b and the fourth portion 22d have a plate
shape.
[0117] As illustrated in FIGS. 8A and 8D, at least a portion of the
second portion 22b faces the first portion 22a and the third
portion 22c. At least a portion of the second portion 22b overlaps
the first portion 22a and the third portion 22c in the up-down
direction. At least a portion of the fourth portion 22d overlaps
the first portion 22a and the third portion 22c in the up-down
direction. The first opening 22x is formed by the second portion
22b and the fourth portion 22d overlapping the first portion 22a
and the third portion 22c.
[0118] The first portion 22a is separated from the second portion
22b and the fourth portion 22d, for example, in the facing
direction, that is, in the up-down direction. The third portion 22c
is separated from the second portion 22b and the fourth portion
22d, for example, in the facing direction, that is, in the up-down
direction.
[0119] The first portion 22a is separated from the second portion
22b and the fourth portion 22d and the third portion 22c is
separated from the second portion 22b and the fourth portion 22d,
for example, respectively, with a predetermined gap in the up-down
direction without contact.
[0120] For the first portion 22a, the second portion 22b, the third
portion 22c, and the fourth portion 22d constituting the
restriction aperture unit 22, for example, those having the same
material and thickness as those in the first embodiment can be
used.
[0121] The support portion 26 supports the restriction aperture
unit 22. The support portion 26 has a first support bar 26a, a
second support bar 26b, a third support bar 26c, and a fourth
support bar 26d. For example, the first portion 22a is supported by
the first support bar 26a. For example, the second portion 22b is
supported by the second support bar 26b. For example, the third
portion 22c is supported by the third support bar 26c. For example,
the fourth portion 22d is supported by the fourth support bar
26d.
[0122] The first portion 22a, the second portion 22b, the third
portion 22c, and the fourth portion 22d are supported at one
location by the first support bar 26a, the second support bar 26b,
and the third support bar 26c, and the fourth support bar 26d,
respectively. Each of the first portion 22a, the second portion
22b, the third portion 22c, and the fourth portion 22d may be
supported by the support portion 26 at a plurality of
locations.
[0123] FIGS. 9A and 9B are explanatory views of the restriction
aperture unit according to the third embodiment. FIG. 9A
illustrates a state in which the opening area of the first opening
22x is small, and FIG. 9B illustrates a state in which the opening
area of the first opening 22x is large.
[0124] The opening area of the first opening 22x of the restriction
aperture unit 22 is variable. For example, by horizontally moving
the support portion 26 in the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 9A is small to the state
where the opening area illustrated in FIG. 9B is large. In
addition, by horizontally moving the support portion 26 in the
direction opposite to the direction of the arrow by driving the
driving motor 24, the opening area can be changed from the state
where the opening area illustrated in FIG. 9B is large to the state
where the opening area illustrated in FIG. 9A is small.
[0125] As described above, similarly to the first embodiment, the
multi charged particle beam writing apparatus according to the
third embodiment can quickly and appropriately control the
temperature of the shaping aperture array substrate 28 by allowing
the opening area of the first opening 22x of the restriction
aperture unit 22 to be variable.
Fourth Embodiment
[0126] A multi charged particle beam writing apparatus according to
a fourth embodiment is different from the multi charged particle
beam writing apparatus according to the first embodiment in that
the multi charged particle beam writing apparatus according to the
fourth embodiment further includes an electrostatic lens.
Hereinafter, a portion of contents overlapping with the first
embodiment will be omitted in description.
[0127] FIG. 10 is a conceptual view illustrating a configuration of
a multi charged particle beam writing apparatus according to the
fourth embodiment. In the fourth embodiment, an electrostatic lens
19 is provided between the illumination lens 18 and the shaping
aperture array substrate 28.
[0128] The electrostatic lens 19 constitutes a lattice lens 29
using the shaping aperture array substrate 28 as a lattice. The
lattice lens 29 reduces the aberration of the illumination system
to narrow the size of the light source image on the stopping
aperture substrate 36. The electrostatic lens 19 is arranged
between the illumination lens 18 and the shaping aperture array
substrate 28.
[0129] In order not to disturb the electric field of the lattice
lens 29, the restriction aperture unit 22 is provided in the
illumination lens 18 or on the side closer to the electron gun
assembly 16 than to the illumination lens 18. FIG. 10 illustrates a
case where the restriction aperture unit 22 is provided in the
illumination lens 18.
[0130] As described above, similarly to the first embodiment, even
in a case where the lattice lens 29 is provided, the multi charged
particle beam writing apparatus according to the fourth embodiment
can quickly and appropriately control the temperature of the
shaping aperture array substrate 28 by allowing the opening area of
the first opening 22x of the restriction aperture unit 22 to be
variable.
Fifth Embodiment
[0131] A multi charged particle beam writing apparatus according to
a fifth embodiment is different from the multi charged particle
beam writing apparatus of the second embodiment in that the
projection lens is omitted and each beam of the multiple beams MB
is directed to the opening of the stopping aperture substrate at an
angle from the restriction aperture substrate. Hereinafter, a
portion of contents overlapping with the first and second
embodiments will be omitted in description.
[0132] FIG. 11 is a conceptual view illustrating a configuration of
a multi charged particle beam writing apparatus according to the
fifth embodiment. In the fifth embodiment, similarly to the fourth
embodiment, the electrostatic lens 19 is provided between the
illumination lens 18 and the shaping aperture array substrate 28,
but the configuration may be the same as that of the first
embodiment.
[0133] Herein, as illustrated in FIG. 11, since the reduction
optical system is configured with the illumination lens 18, the
pitch of the arrangement of the third openings 30x of the blanking
aperture array substrate 30 is smaller than the pitch of the
arrangement of the second openings 28x of the shaping aperture
array substrate 28.
[0134] The beam diameter of the electron beam B gradually decreases
from the time when the electron beam passes through the restriction
aperture unit 22. In addition, the pitch of each beam of the
multiple beams MB gradually decreases from the time when the beam
passes through the shaping aperture array substrate 28. The
multiple beams MB passes through the blanking aperture array
substrate 30 with a smaller pitch than the pitch of each beam
formed by the shaping aperture array substrate 28.
[0135] As described above, similarly to the first embodiment, in a
case where the multiple beams MB travel while narrowing the beam
pitch, the multi charged particle beam writing apparatus according
to the fifth embodiment can quickly and appropriately control the
temperature of the shaping aperture array substrate 28 by allowing
the opening area of the first opening 22x of the restriction
aperture unit 22 to be variable.
[0136] The embodiment has been described with reference to the
specific examples. However, the embodiment is not limited to these
specific examples.
[0137] In the first to third embodiments, the case where the shape
of the first opening 22x of the restriction aperture unit 22 is
rectangular has been described as an example, but the shape of the
first opening 22x is not limited to a rectangular shape. The shape
of the first opening 22x may be, for example, a pentagon or more
polygon or a circle. For example, an iris diaphragm structure using
diaphragm blades can be applied to the restriction aperture unit
22.
[0138] In the first to fifth embodiments, the case where the
charged particle beam writing apparatus is a mask writing apparatus
has been described as an example, but the embodiments can be
applied to, for example, a charged particle beam writing apparatus
that directly draws a pattern on a semiconductor wafer.
[0139] In addition, although the portions that are not directly
necessary for the description of the embodiment such as the device
configuration and the control method are omitted in description,
the required device configuration and control method can be
appropriately selected and used. For example, although the
configuration of the control unit that controls the charged
particle beam writing apparatus is omitted in description, it goes
without saying that the required configuration of the control unit
is appropriately selected and used. In addition, all charged
particle beam writing apparatuses and apertures which include the
elements of the invention and of which design can be appropriately
changed by those skilled in the art are included in the scope of
the invention.
* * * * *